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DRDC Atlantic, in partnership with Netherlands Ministry of Defence, is undertaking a multi-year experimental program to determine the effects of material loss due to corrosion on the strength of submarine pressure hulls. This document presents the results of “Phase 3” of the testing program, which saw the pressure testing of eleven small-scale ring-stiffened aluminium cylinders with various structural configurations and patterns of simulated corrosion damage. The effects of material loss due to corrosion and subsequent grinding were simulated by machining away material from the cylinder shell, resulting in a locally thin patch of material. Intact and corroded cylinders with nominally identical axisymmetric structural configurations were tested in order to allow comparison of the damaged and undamaged cylinder strength. The reduction in collapse pressure due to corrosion was found to be, in percentage terms, on the order of the shell thinning. Yield strength was more greatly affected by thinning, by a factor of approximately two, than collapse strength. The tendency of yielding and collapse to be initiated at the edges of a corrosion patch suggests that the eccentricity due to one-sided shell thinning may have a strength-reducing effect in addition to the thinning itself. Comparison of cylinders with local interframe shell corrosion with those having large areas of multi-bay thinning indicates that the magnitude of thinning is more significant for strength and serviceabili